Large numbers of soldiers were marching into Heaven Dou City. By now, more than two hundred thousand troops had gathered within its walls.
On the third day, Prince Xue Xing invited Dugu Bo to Xue Ye's bedchamber to examine the emperor.
"Mr. Dugu, how is His Majesty's condition?" Prince Xue Xing hurried forward to ask once Dugu Bo finished checking the emperor's pulse.
Dugu Bo did not answer. He rose and walked straight to the incense burner in the room, lifted its lid, and sniffed.
"His Majesty isn't ill," he said. "He's been poisoned!"
"What?!" Both Prince Xue Xing and Xue Ye paled at Dugu Bo's words.
"All my food undergoes strict inspection, and there has never been a problem. Mr. Dugu, could your diagnosis be mistaken?" Xue Ye asked in disbelief.
Dugu Bo shook his head. "The poison didn't come from His Majesty's food, but from the incense burning in this burner. It contains a slow-acting toxin that gradually poisons the body. Now, the concentration in this incense has reached a level that can quickly prove fatal." With a wave of his hand, Dugu Bo extinguished the incense.
"No wonder His Majesty's health has been growing steadily worse lately. Do you have a way to treat him, sir?" Prince Xue Xing asked again.
"No. I've never encountered this compound poison before. I wouldn't know where to begin." Dugu Bo shook his head and sighed.
"Your Majesty, the crown prince requests an audience," an attendant reported as he entered.
"Let him in," Xue Ye said.
Xue Qinghe entered and bowed. "Father."
Turning to see Prince Xue Xing and Dugu Bo standing nearby, he asked, "Uncle, Your Excellency Dugu, what brings you here?"
"Your uncle invited Mr. Dugu to examine me," Xue Ye said.
"Then how is your condition, Father?" Xue